FACE TO FACE
Year : 2014 | Volume
: 4 | Issue : 1 | Page : 65--69
An interview with Dr. T. M. Mohapatra
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Tropical Parasitology (TP): Dear Professor, as a pioneer in parasitology research what do you think about the progress in parasitology research in India over the past few decades?
Dr. T.M. Mohapatra: Parasitology had been an obligatory subject at the veterinary educational institutions. For the purpose of finding solutions to "burning" parasitological problems, a process was brought to enable members to graduate as an expert in parasitology through post-graduation in microbiology. Unfortunately in the subject of microbiology also, parasitology was a neglected one. Baring one or two institutions where parasitology was an independent department the subject was limited to research institutions. Slowly it has picked up. In the late 70s and early 80s few academicians had started conducting research in this field. At present, considerable progress has been made through the collaborative special research program with reference to:
Development of integrated control strategies to strengthen national control programsComprehensive update of the surveillance data on parasitic infections both in humans and animalsImprovement of existing diagnostic tools and/or development of innovative tools to detect parasitic infectionsResearch in the fields of newer drugs and vaccines.
More and more people are joining and I hope that it will pick up the speed in coming decade.
TP: What are your areas of interest in parasitology research?
Dr. T.M. Mohapatra: My research areas involving parasitic diseases are numerous and constitute my primary field of responsibility especially malaria, kala-azar and filariasis, which causes havoc so far as the morbidity and mortality is concerned in our country. These include diagnosis, management of diseases, ecology, pathogenesis, host-parasite relationships and prevention in relation to public health.
TP: What is the current status of the "neglected tropical diseases" (NTDs) in India?
Dr. T.M. Mohapatra: The NTDs represent a group of chronic parasitic, related bacterial and viral infections that actually promote poverty due to their impact on child development, pregnancy outcome and worker's productivity. With a population of 1.13 billion, the total of global disease burden of NTDs in India account for about 292 million where some NTDs still remain undetermined and therefore the present numbers represented above may represent just the tip of the iceberg. Today, South Asia accounts for approximately one-quarter of the world's soil-transmitted helminthic (STHs) infections, one-third or more of the global deaths from rabies and one-half or more of the global burden of lymphatic filariasis, visceral leishmaniasis (VL) and leprosy. Although, leptospirosis is believed to be an important NTD in South Asia, there is a paucity of prevalence and disease burden information. However, due to its association with flooding, leptospirosis is believed to be an important cause of acute febrile illness in children and aseptic meningitis, especially in the monsoon and immediate post-monsoon seasons. The disease is endemic in the Indian states of Kerala (where the seroprevalence is especially high among high-risk groups such as sewage workers, hospital sanitary workers and fisherman), Tamil Nadu and the Adamans and outbreaks are common in the slums of Mumbai. World-wide, trachoma is a leading cause of visual impairment and blindness. According to the World Health Organizations (WHO's) world trachoma atlas using data from 2003, approximately 1 million cases of trachoma occur in India, particularly in Rajasthan. These cases represent less than 5% of the world's trachoma disease burden. However, other sources indicate that India may account for a much larger contribution to the global trachoma disease burden. The region is also experiencing an emerging problem with three major arbovirus infections, i.e. dengue, Japanese encephalitis and chikungunya. For several other important NTDs, such as strongyloidiasis, toxocariasis, leptospirosis and amebiasis, there are no prevalence or disease burden estimates available. Thing appear to be brighter as a recently held meeting of experts on NTDs, the global health progress, Organization of Pharmaceutical Producers of India and International Federation of Pharmaceutical Manufacturers and Associations decided to join hands to eradicate NTDs from India. The launch of this initiative, called "Partnering for Success-Reducing India's Burden of NTDs" was followed-up with a landmark report, launched on the 23 rd December, 2013, on the current status and action plan to fight NTDs in India. Anshu Prakash, Joint Secretary, Union Health Ministry said, "India has supported the London Declaration of 2012 and has joined other member nations at the World Health Assembly this year to adopt a resolution for controlling, eliminating and eradicating 17 identified NTDs. The India government is working with all stakeholders and the community toward meeting these objectives".
TP: As a recognized and eminent research person in leishmaniasis, please enlighten about the disease burden world-wide and in India?
Dr. T.M. Mohapatra: Leishmaniases are endemic in 98 countries with an estimated yearly incidence of 1-1.5 million cases of cutaneous leishmaniasis and 500,000 cases of VL apart from other forms. According to WHO report in South-East Asia Region, about 147 million people in three countries (Bangladesh, India and Nepal) are at risk of kala-azar. Recently, a small focus of kala-azar has been identified in Bhutan. The report published in 2013 shows that from 1987 through 2011, a total of 7, 60, 432 kala-azar cases were reported in India; the data were collected by the different agencies for the Government of India. Annual kala-azar cases ranged from 12,140 in 2002 to 77,102 in 1992, with a mean of reported case per year is about 30417.28. The trend of rising incidence was found in 1990-1993 and 2005-2008. Kala-azar cases were reported from 52 districts (e.g. 4 main states) of India. However, Bihar (31 districts), West Bengal (6 districts), Jharkhand (4 districts) and Uttar Pradesh (UP) (11 districts) were highly affected states by this disease. Furthermore, more than 70-80% kala-azar cases were reported from Bihar only. In 2010, 79.76% positive cases were contributed by Bihar only; whereas 14.87% in Jharkhand, 5.12% in West Bengal and 0.04% in UP, as a proportion of a country. Ten districts of Bihar state (Muzaffarpur, Purnea, Saharsa, Ararea, Vaishali, Madhepura, East Champaran, Samastipur, Saran and Darbhanga) have been reporting more than 75% of the total cases for several years. Most of these districts are located north of the river Ganges. From 1987 to 2011, a total of 670,897 kala-azar cases were reported officially from Bihar only. Annual incidence of kala-azar cases ranged from 1.14 to 8.76/10,000 populations, with an average incidence rate of 3.05. The maximum intensity of disease was found during the period of year from 1990 to 1993. According to this data in 2011, about 30,000 cases were reported from India. However, the number of cases has been below 20,000 in 2012. VL is a common infection for advanced human immunodeficiency virus (HIV)-77-90% of patients: CD-4 count <200 cells/mm. HIV grows less urban while VL grows less rural. Hence, rise of co-infection is in peri-urban areas. Further, newer tools like remote sensing and geographical information systems are being used recently to determine the disease burden and its control.
TP: How successful has been the coverage of goals of "program for elimination of kala-azar in the South-East Asia Region" in India and where do we currently stand? What recommendations would you suggest to be added on to the current program?
Dr. T.M. Mohapatra: According to WHO 2012 report, the strategies are early diagnosis and complete case management, integrated vector management and vector surveillance, effective disease surveillance through passive and active case detection, social mobilization and building partnerships, implementation and operational research and capacity building. I fully endorse the view of WHO Program for elimination of kala-azar in the South-East Asia Region''. It depends on the implementation of the program for the elimination of the disease. They have envisaged in different phases; preparatory phase, attack phase, consolidation phase and maintenance phase. The country is gearing up toward these programs.
TP: In the recent few years, how has the diagnosis of leishmaniasis cases improved?
Dr. T.M. Mohapatra: On principle laboratory diagnosis of leishmaniasis can be made by the following: (i) Demonstration of parasite in tissues of relevance by light microscopic examination of the stained specimen, in vitro culture, or animal inoculation; (ii) detection of parasite deoxyribonucleic acid (DNA) in tissue samples; or (iii) immunodiagnosis by detection of parasite antigen in tissue, blood, or urine samples, by detection of nonspecific or specific antileishmanial antibodies (immunoglobulin), or by assay for Leishmania-specific cell-mediated immunity.
The non-specific test are leucocyte count, hemoglobin estimation, serum protein analysis, study of albumin/globulin ratio, erythrocyte sedimentation rate, liver enzymes and estimation of tumor necrosis factor-α. These are still used as adjunct to clinical diagnosis in many peripheral health care set ups. However, the gold standard for diagnosis is microscopy wherein demonstration of parasite in tissues of relevance by light microscopic examination of the stained specimen, in vitro culture, or animal inoculation is done.
Leishmanin skin test (Montenegro) has become a theoretical option. Newer molecular diagnosis such as DNA hybridization, polymerase chain reaction (PCR), reverse transcription PCR, nested PCR, PCR-single-strand conformation polymorphism, PCR-enzyme-linked immunosorbent assay (ELISA), proteinase K based PCR, flourogenic PCR, PCR followed by restriction fragment length polymorphism are also being used where the facilities are available or in research institutions. There are different serological test such as indirect hemagglution, counter-current immunoelectrophoresis, immunodiffusion, indirect fluorescent antibody test, direct agglutination test (DAT), fast agglutination-screening test, ELISA, antigen detection in urine and immunoblotting. In my observation, rK39 test is one of the most useful tests available currently. Another robust test is DAT. Modifications of these test are also continuously upgraded for case diagnosis as well as field study. If I am asked to choose to test in Indian context for Leshmania donovani infection I will select DAT and rK39 tests.
TP: What are the potential vaccine candidates for leishmaniasis, is a vaccine within a sniffing distance?
Dr. T.M. Mohapatra: Extensive evidence from studies in animal models indicates that solid protection can be achieved by immunization with defined subunit vaccines or live-attenuated strains of Leishmania. However, until date, no such vaccine is available despite substantial efforts by many laboratories. The major impediment in vaccine design is the translation of data from animal models to human disease and the transition from the laboratory to the field. Furthermore, a thorough understanding of protective immune responses and generation and maintenance of the immunological memory, the most important and least-studied aspect of anti-parasitic vaccine development, during Leishmania infection is needed. Until date, several different approaches to antileishmanial vaccine have been tested. First generation vaccines composed of whole killed parasites have been proposed as both prophylactic and therapeutic vaccines. The therapeutic application may be particularly important in cases of drug resistant refractory disease. In theory, these vaccines should be easy to produce at a low cost in endemic countries; however, standardization of cultured parasite-derived vaccines is a drawback in the way to their registration. In general, the whole-cell, killed vaccines have been rather poorly defined and variable in potency; hence, they have rendered inconclusive results. Nevertheless, the trials completed so far demonstrated their good safety profile and despite poor prophylactic outcomes, showed encouraging results as therapeutic vaccines in South America and Sudan.
Most of the vaccine studies concentrate on the second generation vaccines consisting of recombinant proteins, poly-proteins, DNA vaccines or dendritic cells loaded with peptides derived from leishmanial antigens. A variety of different molecules has been tested to date and these included antigens such as surface expressed glycoprotein leishmaniolysin (gp63) delivered by a plethora of immunization regimens, however, promising findings from animal models were overshadowed by mostly negative T-cell responses in humans. Another vaccine candidate has been a glycosylphosphatidylinositol-anchored membrane protein gp46 or parasite surface antigen 2 that belongs to a gene family present in all Leishmania species except L. braziliensis. Immunization with the native polypeptides derived from promastigotes protected mice against infection but vaccination with a recombinant protein derived from either promastigotes or amastigotes protein showed lack of protective efficacy.
Similarly, DNA vaccination conferred protection in mice when used as either prophylactic or therapeutic vaccines. Another extensively tested antigen is the Leishmania homologue for receptors of activated C kinase (LACK) that is expressed throughout leishmanial life cycle Immunization with LACK appears to promote the expansion of IL-4 secreting T cells skewing the response toward detrimental Th2 responses however, susceptible BALB/c mice immunized with LACK had the ability to control a subsequent infection with L. Major until date, the protective efficacy of LACK has been mainly demonstrated in the L. Major model and LACK failed to protect against VL.
Several other antigens from different species have been tested in animal models. These include amastigote cysteine proteases, cysteine proteinase A2 and amastigote membrane proteins P4 and P8, kinetoplastid membrane protein-11, amastigote LCR1, hydrophilic acylated surface protein B1, leishmanial antigen ORFF, acidic ribosomal protein P0, paraflagellar rod protein 2, NH36, a main component of the fucose-mannose ligand and proteophosphoglycan. In addition, molecules such as ATP synthase alpha chain, beta-tubulin and heat shock 70-related protein 1 precursor have been recently identified as novel vaccine candidates.
Until date, only 1 second generation vaccine, Leish-111f, has been assessed in clinical trials Leish-111f is a single polyprotein composed of three molecules fused; the L. major homologue of eukaryotic thiol-specific antioxidant, the L. major stress-inducible protein-1 (LmSTI1) and the L. braziliensis elongation and initiation factor. Initial immunization trials in mice demonstrated that Leish-111f was able to protect mice against L. major and L. amazonensis infection. There is some evidence that the Leish-111f vaccine can also induce partial protection against VL in animal models, however, Leish-111f failed to protect dogs against infection and did not prevent disease development in a recent Phase III trial in dogs. A slightly improved version of the original construct, Leish-110f, has also been tested in dogs as a therapeutic vaccine in combination with chemotherapy and led to reduced number of deaths and higher survival probability. Human Phase I and II clinical trials (safety and immunogenicity) of Leish-111f have been completed over the past few years in Brazil, Peru and Columbia and Phase I trial has been conducted in India.
TP: There has been recent emergence of Leishmania , particularly drug-resistant strains. Please throw some light on drug-resistance in leishmaniasis in India?
Dr. T.M. Mohapatra: Although, the selection of resistant Leishmania has long been a part of laboratory studies, it is only in the past 20 years that acquired resistance that has become a clinical threat. The first indication of drug resistance came from North Bihar, in the early 80s, of about 30% patients not responding to the prevailing regimen of Sb v , which was a small daily dose (10 mg/kg; 600 mg maximum) for short duration (6-10 day). Then two 10-day courses with a 10-day interval therapy with sodium antimony gluconate were recommended by an expert committee leading to a marked improvement in the cure rates up to 99%. However, in the year 1984, it was seen that with 20 mg/kg (maximum 600 mg) for 20 days, 86% of patients were cured. In the same year, the WHO expert committee recommended that pentavalent antimony be used in doses of 20 mg/kg up to a maximum of 850 mg for 20 days and a repetition of similar regimen for 20 days in cases of treatment failures. The WHO recommendations was evaluated a few years later by Thakur et al. and it was reported that only 81% of patients were cured by this regimen, although with an extension of the treatment for 40 days, 97% of patients could be cured. At 3 years later, the same group noted a further decline in cure rate to 71% after 20 days of treatment and recommended extended duration of treatment in non-responder. However, by early 90s, extending the therapy to 30 days could cure only 64% of patients in a hyperendemic district of Bihar. In two studies carried out under strictly supervised treatment schedules, it was observed that only about one-third of the patients could be cured with the currently prevailing regimen. The incidence of primary unresponsiveness was 52%, whereas 8% of the patients relapsed. Incidentally, only 2% of the patients from the neighboring state of (Eastern) UP failed treatment. There are reports of antimony resistance spreading to the Terai regions of Nepal, especially from the district adjoining the hyper endemic areas of Bihar, where up to 30% of the patients seem to be unresponsive, though in Eastern Nepal a 90% cure rate has been reported. These studies confirmed that a high level of antimony resistance existed in Bihar, whereas it was still effective in surrounding areas.
The Indian L. donovani had become truly refractory to Sb v and resistance had occurred due to the inadequate doses being used in Bihar. The reasons for the emergence of resistance were the widespread misuse of the drug. Sb v as it is freely available in India, both qualified medical practitioners and unqualified quacks used the drug and this unrestricted availability of the drug led to rampant misuse. Almost 73% of patients consulted unqualified practitioners first; most of them did not use the drug appropriately. These practices resulted in build-up of sub therapeutic blood levels and increased tolerance of parasites to Sb v .
Almost half of the patients, receiving pentamidine as a second-line drug, had not received adequate antimony treatment before being labeled as refractory to Sb v . There were several manufacturers of Sb v in India and quality of products were inconsistent, resulting in occasional batches being substandard and toxic, this added to the problems associated with Sb v therapy causing serious toxicity and deaths related to the drug.
Another reason for the growing resistance to Sb v in India while it still remained sensitive all over the world could be due to the fact that leishmaniasis usually has zoonotic transmission except in the Indian subcontinent and East Africa where the transmission is largely anthroponotic. In an anthroponotic cycle once Sb v resistance gets established, it spreads exponentially and organisms sensitive to the drug get eliminated quickly, whereas the drug-resistant parasites continue to circulate in the community.
HIV/VL coinfected patients is another subset who respond poorly to Sb v , as the drug needs an intact immune system to be effective and the response is not as good as in immunocompetent patients.
TP: What is the status of research in leishmaniasis in India? Are the research facilities deficient in our country?
Dr. T.M. Mohapatra: The search for lead molecules with antileishmanial activity, without toxic effects and able to overcome the emergence of drug resistant strains, also remain the current goal in may research institutes. Microarray monitoring of gene expression in drug is being carried out in unresponsive clinical isolates collected from the disease endemic regions. Other areas such as improvement in the diagnostic tool, finding out an alternative chemotherapeutic agent for resistant kala-azar, its control measures and of course vaccine for kala-azar are being studied. We have adequate facilities in our country and our researchers are devoted and talented. What we lack is the system, political will and implementation.
TP: What are your valuable suggestions for the budding researchers in parasitology?
Dr. T.M. Mohapatra: Parasitology per se is a neglected branch. However it affects millions of people in India in terms of mortality and morbidity especially in the underprivileged and the poorest of the poor community. I would suggest the budding researchers to serve the community which is affected by the "NTDs", "STHs" infections and of course malaria and kala-azar. Service to Humanity is service to GOD.
To encourage the young scientist the curriculum in the medical institutions may be modified and there should be multidisciplinary approach involving other specialties. The research should be translational.
TP: How to take the research in parasitology forward?
Dr. T.M. Mohapatra: The total number of protozoal and helminthic infections far out numbers the world's population since multiple infections are rule in tropical areas. The diseases remain among the most ubiquitous and serious public health problem with high prevalence rates of major protozoal and helminthic infection. They will be with us for an unpredictable length of time certainly in the 21 st century which WHO has chosen for its slogan "Health for all" Everybody is aware of the work of WHO and its activities in parasitic diseases since its foundation. Prevailing environmental and social background condition leads to re-infection and perpetuation of epidemiological transmission cycle. Cumulative negative an impact on agriculture and industry affecting food supply on the face of increasing population. There is an urgent need for the policy makers to create a Department of Medical Parasitology OR Tropical Parasitology and Entomology to ensure the training of doctors, teachers and research workers. Motivation and mentoring of the seniors are also very important issue.
TP: Please shed some light on the soil transmitted helminthes and their control in India
Dr. T.M. Mohapatra: The tropics and subtropics have widespread infection with all three STH, namely Ascariasis (in India of 1130 million population, 808 million at risk, 14% prevalence, having 140 million as total estimated number of infections). Trichuriasis (398 million at risk, 7% prevalence, 73 million total estimated number of infections). Hookworm (534 million at risk, 7% prevalence, 71 millions of total estimated number of infections). The poor economic growths of some countries contribute to the poor level of sanitation resulting in high prevalence of STHs.
The WHO urges member states to ensure access to good quality anthelminthic drugs at all levels of the health care system in endemic areas. Regular treatment of school children and other at-risk groups (such as pre-school children, pregnant women and special occupation groups) will help to avoid the worst effects of infection, even if there is no improvement in safe water supply or sanitation.
STH infections must still be considered as the most prevalent infections of humankind. Although, in some regions of India, there has been a precipitous decline in STH prevalence, primarily because of economic development and specific control, public health measures and educational programs are in progress but the pace is slower.